The present invention relates to a semiconductor storage device such as mask ROM (mask read only memory) and so forth with more high integration and high speed operation. More to particularly, this invention relates to a semiconductor storage device for the sake of the mask ROM in which a plurality of memory cell transistor (Tr) are connected with every one bit contact due to the fact that it causes main/sub bit line constitution and virtual GND system to be adopted in order to realize large capacity mask ROM with high integration and high speed access.